From patchwork Sun Mar 1 13:03:18 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jean Delvare X-Patchwork-Id: 9445 Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n21D3UBi002675 for ; Sun, 1 Mar 2009 13:03:31 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752827AbZCANDb (ORCPT ); Sun, 1 Mar 2009 08:03:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752956AbZCANDa (ORCPT ); Sun, 1 Mar 2009 08:03:30 -0500 Received: from zone0.gcu-squad.org ([212.85.147.21]:7545 "EHLO services.gcu-squad.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752827AbZCANDa (ORCPT ); Sun, 1 Mar 2009 08:03:30 -0500 Received: from jdelvare.pck.nerim.net ([62.212.121.182] helo=hyperion.delvare) by services.gcu-squad.org (GCU Mailer Daemon) with esmtpsa id 1LdmOG-0005Md-B0 (TLSv1:AES256-SHA:256) (envelope-from ) ; Sun, 01 Mar 2009 15:11:36 +0100 Date: Sun, 1 Mar 2009 14:03:18 +0100 From: Jean Delvare To: Zhang Rui Cc: linux-acpi@vger.kernel.org, Len Brown Subject: [PATCH] ACPI: Adjust Kelvin offset to match local implementation Message-ID: <20090301140318.5cf56287@hyperion.delvare> X-Mailer: Claws Mail 3.5.0 (GTK+ 2.14.4; x86_64-suse-linux-gnu) Mime-Version: 1.0 Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org The exact offset between Kelvin and degree Celsius is 273.15. However ACPI handles temperature values with a single decimal place. As a consequence, some implementations use an offset of 273.1 and others use an offset of 273.2. Try to find out which one is being used, to present the most accurate and visually appealing number. Tested on a Sony Vaio PGC-GR214EP (which uses 273.1) and a Lenovo Thinkpad T60p (which uses 273.2). Signed-off-by: Jean Delvare Cc: Zhang Rui Cc: Len Brown Acked-by: Zhang Rui --- Blame the mess on whoever decided that ACPI temperature would be expressed in the least adapted unit in the world :( Without this patch, I have the following sensors output: acpitz-virtual-0 Adapter: Virtual device temp1: +44.9 C (crit = +89.9 C) With the patch I instead have: acpitz-virtual-0 Adapter: Virtual device temp1: +45.0 C (crit = +90.0 C) Which I think is much easier to read. drivers/acpi/thermal.c | 42 +++++++++++++++++++++++++++++++++++------- 1 file changed, 35 insertions(+), 7 deletions(-) --- linux-2.6.29-rc6.orig/drivers/acpi/thermal.c 2009-01-17 09:06:19.000000000 +0100 +++ linux-2.6.29-rc6/drivers/acpi/thermal.c 2009-03-01 13:51:45.000000000 +0100 @@ -193,6 +193,7 @@ struct acpi_thermal { struct timer_list timer; struct thermal_zone_device *thermal_zone; int tz_enabled; + int kelvin_offset; struct mutex lock; }; @@ -952,7 +953,7 @@ static void acpi_thermal_check(void *dat } /* sys I/F for generic thermal sysfs support */ -#define KELVIN_TO_MILLICELSIUS(t) (t * 100 - 273200) +#define KELVIN_TO_MILLICELSIUS(t, off) (((t) - (off)) * 100) static int thermal_get_temp(struct thermal_zone_device *thermal, char *buf) { @@ -966,7 +967,8 @@ static int thermal_get_temp(struct therm if (result) return result; - return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(tz->temperature)); + return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS(tz->temperature, + tz->kelvin_offset)); } static const char enabled[] = "kernel"; @@ -1061,21 +1063,24 @@ static int thermal_get_trip_temp(struct if (tz->trips.critical.flags.valid) { if (!trip) return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS( - tz->trips.critical.temperature)); + tz->trips.critical.temperature, + tz->kelvin_offset)); trip--; } if (tz->trips.hot.flags.valid) { if (!trip) return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS( - tz->trips.hot.temperature)); + tz->trips.hot.temperature, + tz->kelvin_offset)); trip--; } if (tz->trips.passive.flags.valid) { if (!trip) return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS( - tz->trips.passive.temperature)); + tz->trips.passive.temperature, + tz->kelvin_offset)); trip--; } @@ -1083,7 +1088,8 @@ static int thermal_get_trip_temp(struct tz->trips.active[i].flags.valid; i++) { if (!trip) return sprintf(buf, "%ld\n", KELVIN_TO_MILLICELSIUS( - tz->trips.active[i].temperature)); + tz->trips.active[i].temperature, + tz->kelvin_offset)); trip--; } @@ -1096,7 +1102,8 @@ static int thermal_get_crit_temp(struct if (tz->trips.critical.flags.valid) { *temperature = KELVIN_TO_MILLICELSIUS( - tz->trips.critical.temperature); + tz->trips.critical.temperature, + tz->kelvin_offset); return 0; } else return -EINVAL; @@ -1649,6 +1656,25 @@ static int acpi_thermal_get_info(struct return 0; } +/* + * The exact offset between Kelvin and degree Celsius is 273.15. However ACPI + * handles temperature values with a single decimal place. As a consequence, + * some implementations use an offset of 273.1 and others use an offset of + * 273.2. Try to find out which one is being used, to present the most + * accurate and visually appealing number. + * + * The heuristic below should work for all ACPI thermal zones which have a + * critical trip point with a value being a multiple of 0.5 degree Celsius. + */ +static void acpi_thermal_guess_offset(struct acpi_thermal *tz) +{ + if (tz->trips.critical.flags.valid && + (tz->trips.critical.temperature % 5) == 1) + tz->kelvin_offset = 2731; + else + tz->kelvin_offset = 2732; +} + static int acpi_thermal_add(struct acpi_device *device) { int result = 0; @@ -1675,6 +1701,8 @@ static int acpi_thermal_add(struct acpi_ if (result) goto free_memory; + acpi_thermal_guess_offset(tz); + result = acpi_thermal_register_thermal_zone(tz); if (result) goto free_memory;